Bump to MicroPython 1.28.0

[sienczak]

As MicroPython v1.28.0 has been freshly released, is there some plan to update default version of MicroPython also here? I have just tested update (only by switching lib/micropython submodule to version v1.28.0 locally) and it seems to be working nearly effortlessly, at least for unix and esp32 port (espidf stays the same 5.5.1 version as before). However I have no clue how about the rest of supported platforms.

[kdschlosser]

I usually like to let new release sit and simmer for a bit so any new bugs can be found and if the bug is not a major one I can patch it in the build script. If it is a bigger more complex issue then I will wait for the next release. The only really notable thing that was done with the ESP32 port was the addition of the LDO for the P4. other than that there has not been anything that would be a wow or finally kind of a reaction from it. Give it another 2 weeks ish and then I will update it.